TaqI-A polymorphism linked to the DRD2 gene and P300 in alcoholic patients

Résumé

Background and Objectives: Different studies carried out mainly in young non-consuming children of alcoholics show an association of P300 abnormalities with alcoholism and with the T aqI- A1 allele. Since the relationship between P300 and the T aqI- A1 allele has not been specifically studied in alcoholic patients, our objective was to investigate whether the association exits in this population. Methods: Our sample consisted of 176 recently detoxified male alcohol-dependent patients. These patients had been alcohol dependent from a mean age of 22.6 years and consumed on average 164.63 (± 142.99) cm 3 of alcohol daily. P300 was studied using an auditory paradigm. T aqI -A polymorphism genotyping was performed. The association between P300 and T aqI- A, and correlation with age and alcohol consumption, was studied. Results: The T aqI- A1 allele was found in 38.6% of our patients (n = 68). The latency and amplitude of P300 were 361.64 milliseconds and 17.53 microvolts, respectively. P300 wave latency in alcoholic patients was longer than the reference value obtained from a sample of healthy men of the Event-Related Potentials Unit (p < 0.001). Alcoholic patients who carried the T aqI -A1 allele showed more prolonged P300 latency than non-carriers, and these in turn more than the control subjects. P300 characteristics varied according to age, but an associa- tion with amount of alcohol or number of years consuming was not found. Conclusions: There is a relationship between the T aqI -A polymorphism and P300 wave characteristics in alcoholic patients. Further investigations need to be carried out in non- consuming alcoholic patients and in healthy control subjects to confirm this association and to clarify the possible influence of the neurotoxic effects of alcohol on P300 physiology.